Recently, various notebook type or laptop type portable personal computers have been developed. Of these computers, there is a computer that can use an external device, called “docking station”, “docker”, or “port replicator”.
An external device includes a display connection terminal configured to connect an external display. In a state in which the computer is attached to the external device, a port of a display control circuit within the computer is connected to the display connection terminal through the external device. Therefore, the computer may use the external display, which is connected to the display connection terminal of the external device, as a display monitor of the computer.
Incidentally, in recent years, as a type of an external display increases, mounting a plurality of display connection terminals on an external device is beginning to be required.
However, if using a configuration in which the plurality of display connection terminals of the external device is connected to the ports of the display control circuit within the computer one to one, it is necessary to increase the number of the ports included in the display control circuit within the computer. The increase in the number of the ports included in the display control circuit may be factor causing a cost increase of the computer.
Also, in many portable personal computers, a display control circuit is embedded into a central processing unit. Therefore, increasing the number of ports included in the display control circuit is not practical.
Therefore, there is a need for implementing new technique which can mount a plurality of display connection terminals on an external device without increasing the number of ports included in the display control circuit.